Path: utzoo!attcan!uunet!mcsun!ukc!pyrltd!root44!gwc
From: gwc@root.co.uk (Geoff Clare)
Newsgroups: comp.unix.internals
Subject: Re: abort may return (was: Re: Checking Exit Codes)
Message-ID: <2518@root44.co.uk>
Date: 5 Nov 90 14:03:04 GMT
References: <18647@rpp386.cactus.org> <4057@awdprime.UUCP> <18658@rpp386.cactus.org> <8508@scolex.sco.COM> <18665@rpp386.cactus.org>
Organization: UniSoft Ltd., London, England
Lines: 33

In <18665@rpp386.cactus.org> jfh@rpp386.cactus.org (John F. Haugh II) writes:

>the normal trick is to set SIGIOT to SIG_DFL, which prevents the signal
>handler from ever catching SIGIOT.  this isn't all that far-fetched as
>other library routines catch certain signals, dork around a bit, then
>re-send the same signal they just caught.

>a conforming implementation might be

>void 
>abort (void)
>{
>	signal (SIGABRT, SIG_DFL);
>	kill (getpid (), SIGABRT);
>	exit (1);
>}

If SIGABRT is being caught, the above will prevent the signal handler
from being called.  It should be:

void 
abort (void)
{
	(void) raise(SIGABRT);
	(void) signal(SIGABRT, SIG_DFL);
	(void) raise(SIGABRT);
	exit (1);
}

A POSIX version should unblock SIGABRT as well.
-- 
Geoff Clare <gwc@root.co.uk>  (Dumb American mailers: ...!uunet!root.co.uk!gwc)
UniSoft Limited, Hayne Street, London EC1A 9HH, England.   Tel: +44-71-315-6600